Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new approach to facilitate immobilization and affinity purification of recombinant proteins and selected human B lymphocytes has been developed. Using magnetic beads with attached DNA containing the Escherichia coli lac operator, fusion proteins comprising the DNA-binding lac repressor could be affinity-purified and recovered by gentle elution conditions, such as with a lactose analogue or by enzymatic means using either deoxyribonuclease (DNase) or restriction endonucleases. The results show for the first time that a DNA-binding protein can be used for affinity purification of fusion proteins as exemplified by the specific and gentle recovery of beta-galactosidase and alkaline phosphatase from bacterial lysates using immunomagnetic separation. The approach was further extended to cell separation by the efficient recovery and elution of human CD37 B lymphocytes from peripheral blood.
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PMID:Immobilization and recovery of fusion proteins and B-lymphocyte cells using magnetic separation. 847 Nov 67

Hypoxia-inducible factor 1 alpha (HIF1alpha) and its related factor, HLF, activate expression of a group of genes such as erythropoietin in response to low oxygen. Transfection analysis using fusion genes of GAL4DBD with various fragments of the two factors delineated two transcription activation domains which are inducible in response to hypoxia and are localized in the C-terminal half. Their sequences are conserved between HLF and HIF1alpha. One is designated NAD (N-terminal activation domain), while the other is CAD (C-terminal activation domain). Immunoblot analysis revealed that NADs, which were rarely detectable at normoxia, became stabilized and accumulated at hypoxia, whereas CADs were constitutively expressed. In the mammalian two-hybrid system, CAD and NAD baits enhanced the luciferase expression from a reporter gene by co-transfection with CREB-binding protein (CBP) prey, whereas CAD, but not NAD, enhanced beta-galactosidase expression in yeast by CBP co-expression, suggesting that NAD and CAD interact with CBP/p300 by a different mechanism. Co-transfection experiments revealed that expression of Ref-1 and thioredoxin further enhanced the luciferase activity expressed by CAD, but not by NAD. Amino acid replacement in the sequences of CADs revealed a specific cysteine to be essential for their hypoxia-inducible interaction with CBP. Nuclear translocation of thioredoxin from cytoplasm was observed upon reducing O2 concentrations.
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PMID:Molecular mechanisms of transcription activation by HLF and HIF1alpha in response to hypoxia: their stabilization and redox signal-induced interaction with CBP/p300. 1020 54

The senescence of human mesenchymal stem cells (hMSCs) causes disruption of tissue and organ maintenance, and is thus an obstacle to stem cell-based therapies for disease. Although some researchers have studied changes in the characteristics of hMSCs (decreases in differentiation ability and self-renewal), comparing young and old ages, the mechanisms of stem cell senescence have not yet been defined. In this study, we developed a growth curve for human bone marrow derived MSCs (hBMSCs) which changes into a hyperbolic state after passage number 7. Senescence associated beta-galactosidase (SA beta-gal) staining of hBMSCs showed 10% in passage 9 and 45% in passage 11. We detected an increase in endogenous superoxide levels during senescence that correlated with senescence markers (SA beta-gal, hyperbolic growth curve). Interestingly, even though endogenous superoxide increased in a replicative senescence model, the expression of APE1/Ref-1, which is sensitive to intracellular redox state, decreased. These effects were confirmed in a stress-induced senescence model by exogenous treatment with H(2)O(2). This change is related to the p53 activity that negatively regulates APE1/Ref-1. p21 expression levels, which represent p53 activity, were transiently increased in passage 9, meaning that they correlated with the expression of APE1/Ref-1. Overexpression of APE1/Ref-1 suppressed superoxide production and decreased SA beta-gal in hBMSCs. In conclusion, intracellular superoxide accumulation appears to be the main cause of the senescence of hBMSCs, and overexpression of APE1/Ref-1 can rescue cells from the senescence phenotype. Maintaining characteristics of hBMSCs by regulating intracellular reactive oxygen species production can contribute to tissue regeneration and to improved cell therapy.
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PMID:Downregulation of APE1/Ref-1 is involved in the senescence of mesenchymal stem cells. 1949 97

We have reported a possible involvement of apurinic/apyrimidinic endonuclease 1 (APE1), one of the DNA repair pathways, in various nephropathy models and found that there is a close connection between APE1 and p53-dependent apoptosis. Therefore, we investigated the changes of APE in aging rat kidney since aging is the consequence of increased susceptibility to apoptosis and impaired repair. Characteristics of chronological aging were compared among 6-, 24- and 28-month-old male Sprague-Dawley rats. Serum blood urea nitrogen and creatinine were measured for renal function. Western blot assay was compared for p53, bax, cleaved caspase 3, rH2AX, and APE1. Immunohistochemical staining of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and APE1 was performed. Cellular senescence was checked by beta-galactosidase staining. Compared with young rats, aged rats showed significant increase in creatinine level with cellular senescence in the proximal convoluted tubules confirmed by beta-galactosidase staining. All the checked variables were significantly increased with aging: 1) increased p53, bax, and caspase 3 may activate the apoptotic pathway, 2) increased rH2AX and 8-OHdG immunolocalization in the proximal convoluted tubules might mean augmented DNA damage, and 3) increased APE1 might be caused by the immunoreactivity in the distal convoluted tubules while decreased in the proximal convoluted tubules. These results suggested that APE1 might have little protective effects on p53-dependent apoptosis irrespective of DNA repair activities in aged renal proximal tubules. Therefore, researchers should use older animals than 24-month-old rats in future studies for investigating the relationship between the apoptosis and DNA repair in the aging kidneys.
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PMID:Apurinic/apyrimidinic endonuclease 1 on aging-associated deteriorations in rat kidneys. 2536 96


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